1. Field of the Invention
The present invention relates to a motor.
2. Description of the Related Art
Conventionally, hydraulic power steering is used in a vehicle such as a passenger car or the like to assist an operator in maneuvering the vehicle. The hydraulic power steering apparatus uses a pump operated by an engine of the vehicle to generate a force to assist the operator in steering the vehicle. In recent years, electric power steering which uses a motor operated by a vehicle battery has become available. Such a system is more power efficient than the conventional hydraulic power steering.
The motor used in such an electric power steering system is expected to operate reliably for a long period of time in various environments. In order to achieve the expected durability and reliability, the motor includes multiple layers of security features.
For example, a power steering unit which includes a control unit having a block mechanism operable to block the electric current conducted to a motor in case of emergency situations is available. Such a control unit is arranged via a heat sink at one axial end of the motor having a substantially cylindrical shape which includes a cylindrical stator and a rotor arranged inside the stator. Such a motor includes a sensor which detects an angular position of the rotor relative to the stator.
In such a motor, terminals having a substantially annular shape for connecting the coils to an external power source may be retained by a holder and arranged at an upper area of the stator or the rotor, wherein a resolver which detects the rotary position of the rotor is arranged above the holder.
In general, when such a block mechanism is arranged inside the control unit and outside of the motor, wiring is arranged between the motor and the control unit, and the block mechanism and the stator. However, when external shocks and/or vibrations are applied to the motor, the wiring between the motor and the control unit may be damaged which compromises the reliability of the motor.
Also, such a motor is expected to have small dimensions in order to improve fuel efficiency and for environmental purposes.